Meeting Abstract

6.6  Saturday, Jan. 4 09:15  Simple robotic models of aquatic locomotion LAUDER, G. V.; Harvard University glauder@oeb.harvard.edu

Robotic models of aquatic locomotion have many advantages over studying live animals, including the ability to manipulate and control individual morphological or kinematic factors that affect performance, substantially easier measurement of locomotor forces and torques, and the ability to abstract complex organismal designs into simpler components. Such simplifications, while not without their drawbacks, facilitate interpretation of how individual traits alter swimming performance and the discovery of underlying physical principles. In collaboration with a number of colleagues, we have been engaged in using a robotic flapping foil apparatus to investigate several key features of aquatic propulsion. This robotic device allows programming of heave (side-to-side) and pitch (angular) motions at the leading edge of both rigid and flexible swimming bodies, and investigation of how changing frequency and Strouhal number affects cost of transport and efficiency. Measurement of three forces and three torques on the flapping object is synchronized with the digital motion program and high-speed video of fluid flow over the foil using particle image velocimetry. Using this robotic system we have investigated (1) resonant effects of swimming foils of different stiffnesses, and the effects of structural resonance on propulsive efficiency, (2) the hydrodynamic effect of simplified tubercle structure on the leading edge of swimming bodies, (3) the effect of non-linearities along the length of swimming foils on locomotor performance, and (4) the effect of specialized engineered drag-reducing surfaces on swimming efficiency. Selected results from these studies will be discussed in detail to illustrate the utility of even simple robotic models for uncovering new features of aquatic propulsion.